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                         *  F  E  A  T  U  R  E  S  *

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                        The incredible shrinking system


    Imagine a robot  surgeon  so  small  that  it  can  be  injected  into  the
bloodstream,  or  a miniature computer  that   can  store  10  million times as
much data as the most powerful mainframe.
    Scientists  today are already working on  techniques that  will  make  this
possible  although, admittedly,  not   until   the   next  millennium.    Known
as  nanotechnology,   the   technique    of   manufacturing  to tolerances of a
billionth of a metre is now  the  object of active research worldwide.
    The  Japanese  Ministry of International  Trade  and  Industry  (Miti)  has
already  provided 95m research,  while   in   the  UK  nanotechnology   is  the
focus  of  a  6m  Link  programme   of  collaborative research between academia
and industry.
    Yet  true  nanotechnology is still a  dream.   The best  we  can  hope  for
now  is  micromechanics,  the   technology   of   producing   millimetre  sized
tolerances.  These devices, which  include  the  silicon  sensors that are just
beginning  to  enter  general   use    in    cars,    use  standard  electronic
manufacturing techniques  such  as  chemical etching, photolithography and thin
film deposition.  Now  'smart' sensors complete with pre-processing electronics
or  full  signal processing are just beginning to take off.
    Other  micromechanical  devices  include  actuators   that  can  adjust the
position of read heads in cd players and vcr  spindles  and heads.
    UK  expertise in this area is concentrated on  techniques  for  fabrication
to   very    high    tolerances     and     associated   instrumentation.   For
example,  Cranfield  Precision   Engineering,   associated    with    Cranfield
Institute   of   Technology    in  Bedfordshire,  has  produced  the Nanocentre
250,  a  three  axis  computer   numerical   controlled system with  resolution
down  to  1.25nm.
    At  the  National   Physical   Laboratory   in   Teddington,   research  is
concentrating  on  nanometre  metrology.    The  laboratory's  engineers   have
designed measuring instruments  with  ranges  from  0.05  to  15nm  for optical
systems.  Techniques for measuring roundness  down   to  1nm  and  displacement
calibration  to  0.01nm  have  also  been  achieved.
    UK  research has  been  co-ordinated  under  the   Link   programme,  under
which  two  industrial  partners  and   one   higher   education  establishment
collaborate.   There  are  already   five  nanotechnology   projects   underway
including micromachining by focused  ion   beams   and ultraprecision machining
research.
    As  Dr David Robinson of  the  mechanical  and optical  metrology  division
of  the NPL and  the  Link  nanotechnology   programme   co- ordinator  pointed
out,   the   priority   areas    for    funding    are   machining   and   nano
positioning and control  for  photonic  and  optoelectronic devices.
    "But  future  directions  could  be   ultra   small  computers  a  thousand
times  faster  and with a   million   times   the  memory,  microscopic  robots
and perfect crystals," he said at   a   recent  Institute of Physics conference
on the subject.  "If you can make  the case there will be sufficient funding."
    The  Japanese  are, not  surprisingly,  keen  on  nanotechnology  research.
In  fact Professor  Norio  Tangaguchi,   an   influential   Japanese  academic,
coined the term in 1974.  But much   of   their  research  is  not performed as
part of  a  systematic  programme,  according   to  Kiyoshi Lizuka who runs the
Research  Development  Corporation of Japan's Yoshida nanotechnology project.
    The  nanomechanism  project, one of the few  ordered  research  efforts  in
nanotechnology, has covered  mainly   techniques   for  optical  devices.   For
example, a one axis stage   mechanism   for   nanometre  positioning  has  been
designed  using  a  synchronous  linear motor and rolling ball guide to give an
accuracy of nm and  a maximum speed of 200nm/s.
    "Precise  position  control   technology   has   been   advanced   by   the
semiconductor and equipment industries in  companies such as  NEC,  Mitsubishi,
Nikon  and  Canon   because   they   require   the   most   advanced technology
themselves", said Lizuka.
    The  Japanese  team  has  also   used  a  scanning   tunnelling  microscope
(stm) to observe features that are less then  1nm  in  size.  In fact they have
actually observed how structures form in  semiconductor substrates.
    "We  have built an  stm  which  we  positioned  on  top  of   a  wafer  and
inspected small areas on unbroken, patterned silicon  wafers  of up to 150nm in
diameter," he said.  "This microscope  has three  micromanipulator probes which
are used to provide voltage  inputs  to transistor structures on the wafer."
    Stm  techniques are  also  being  widely  used  in  the   US.    "Stms  are
becoming a key factor in the development  of nanotechnology in  the  US,"  said
Dr Clayton Teague of the  National   Institute  of  Standards and Technology in
Maryland.
    Last  year scientists  at  IBM's  Almaden  Research  Centre  in   San  Jose
pinned  down single atoms using  an  stm.   A  needle   tip  was  passed over a
surface to detect bumps of protruding atoms, then a  burst  of current was used
to stick single atoms  to   the   surface   and   pull  them  off.  Admittedly,
though,  this  experiment   was   performed  on  xenon  atoms  at liquid helium
temperatures.
    Eventually  this  technique could  be  used  with  semiconductor  materials
to  manufacture  minute  devices  and   even   complete  machines, according to
Dr Teague.
    In fact, the method of building up structures atom by atom was  the goal of
the late US physicist, Professor Richard  Feynman.   In  a lecture at Christmas
1959  meeting  of  American  Physical   Society   at  California  Institute  of
Technology entitled "There's plenty  of   room  at  the  bottom",  he made some
startling predictions.
    According  to  Prof  Feynman,  we  could  store   all  50  million  volumes
every published in a 'book' the size of a speck of  dust,  while  a  car  could
be miniaturised  4000  times  and   molecular   computers  could think like the
human brain.


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